A structure including titanium nitride film/hafnium oxide film/titanium nitride film (TiN/HfO2/TiN) has been suggested for formation of a capacitor having a reduced leakage current and an increased capacitance. Since a capacitor including a TiN/HfO2/TiN structure may be less expensive and may further possess a lower current density than a structure including ruthenium film/tantalum oxide film/ruthenium film (Ru/TaO2/Ru), which is representative of a metal-insulator-metal (MIM) capacitor, the TiN/HfO2/TiN structure may be applied to a semiconductor memory device that may be limited to a design rule of 100 nm or less. However, a capacitor having the TiN/HfO2/TiN structure may generate a larger leakage current during a back-end process.
To address this problem, a layer, such as an aluminum oxide (Al2O3) layer, may be disposed between hafnium oxide (HfO2) layers in order to delay crystallization of the HfO2 layers as discussed in Korean patent application No. 2004-0067433. Since the crystallization temperature of the Al2O3 layer may be higher than that of the HfO2 layers, crystallization of the HfO2 layers may be delayed at least in part because of the increase of the total crystallization temperature of the capacitor dielectric film when the back-end process is performed at a higher temperature, thereby reducing or preventing generation of the larger leakage current.
Since the entire thickness of a conventional hafnium oxide film/aluminum oxide film/hafnium oxide film (HfO2/Al2O3/HfO2) structure is about 100Å or less, a single type atomic layer deposition (ALD) apparatus may be used for depositing the films. However, since a respective process may be performed for each wafer when the single type ALD apparatus is used, formation of dielectric films on several wafers may require additional time, resulting in a lower throughput.
Additionally, in order to reduce operation time, the HfO2/Al2O3/HfO2 structure may be deposited in-situ at about 250 to 350° C. in order to form a conventional MIM capacitor. However, when the Al2O3 film is deposited at about 250 to 350° C., the film may be thermally degraded such that a sufficiently high crystallization temperature of the Al2O3 film may not be obtained. Therefore, the Al2O3 film may not increase the crystallization temperature of the capacitor dielectric film.
Further, MIM capacitors may be formed on 200 mm caliber wafers, and increasingly, on 300 mm large caliber wafers. However, MIM capacitors formed on 300 mm large caliber wafers using conditions for forming MIM capacitors on 200 mm wafers may render it problematic to obtain optimized MIM capacitors.